Electrospray ionization-tandem mass spectrometry investigation of polymerization of tetrahydrofuran initiated by phosphorus oxychloride

Phosphorus oxychloride was found to induce ring opening of tetrahydrofuran (THF) to synthesise THF oligomer incorporated phosphate. ESI multi-stage tandem mass spectrometry was used to study the products and confirm the structures.     

Cationic polymerization of vinyl monomers initiated by phosphorus compounds containing halogens

Polymerization of vinyl monomers having large negative e values in the presence of phosphorus compounds containing halogens was studied in order to examine the cationic initiation ability of phosphorus compounds. N-Vinylcarbazole was effectively polymerized by phosphorus compounds such as PCI₃, PBr₃, PCI₂C₆H₅, PCI(C₆H₅)₂, POCI₃, and POCI₂C₆H₅ even in benzene. The initiation ability of phosphorus compounds decreased in the order; PCI₂ ? PBr₃ > PCI₂C₆H₅ > PCI(C₆H₅)₂, and also POCI₃ > POCI₂₆₅. On the other hand, PCI₃ and PBr₃, which were less effective than POCI₃, showed initiation ability for the polymerizations of styrene and α-methylstyrene in nitrobenzene as a solvent. The results of the copolymerization of styrene with methyl methacrylate by PCI₃ in nitrobenzene, the result of solvent dielectric constant effect, and the effect of additives such as water, tert-butyl chloride, triethylamine, and hydroquinone, indicate the polymerization of styrene by PCI₃ to proceed by a cationic mechanism.     

Cationic graft copolymerization of styrene onto poly(vinyl chloride) initiated by phosphorus trichloride

The effect of some organic halides on the cationic polymerization of styrene (St) initiated by phosphorus trichloride (PCl₃) was studied to clarify the initiation mechanism on the cationic polymerization. Addition of organic halides caused an acceleration to some extent. Further, cationic graft copolymerization of St onto poly(vinyl chloride) and polychloroprene was carried out. In each case, grafting efficiency was lower than 10%. These results in the cationic polymerization of St by PCl₃ in nitrobenzene support the assumption that the initiation step is caused by the dissociation of two molecules of PCl₃ to ion pairs.     

Nitroxide-mediated styrene polymerization initiated by an oxoaminium chloride

An oxoaminium chloride that is prepared by reacting 2,2,6,6-tetramethylpiperidinyl-1-oxy (TEMPO) with chlorine in carbon tetrachloride initiates radical polymerization of styrene at 120°C. In the early stages of polymerization, a monomeric adduct, 2,2,6,6-tetramethyl-1-(2-chloro-1-phenylethoxy)piperidine, is formed. Thereafter, styrene polymerization exhibiting the characteristics of living polymerization proceeds. High molecular weight polymers with relatively narrow molecular weight distributions are obtained by this polymerization. ¹H-NMR spectra of the polymers reveal that a chlorine atom and a TEMPO group are present at the α- and ω-termini, respectively. The monomeric adduct was prepared by heating the oxoaminium chloride and styrene in carbon tetrachloride at 65–70°C, and was characterized by ¹H- and ¹³C-NMR spectroscopy. It was found to be suitable as an initiator for nitroxide-mediated radical polymerization of styrene to make polymers with chlorine on the chain end. © 1998 John Wiley & Sons, Inc. J. Polym. Sci. A Polym. Chem. 36: 2555–2561, 1998     

Effects of phosphorus oxychloride and phenylphosphonic dichloride on the radical polymerization of methyl methacrylate and styrene

Effects of pentavalent phosphorus compounds on the radical polymerization of methyl methacrylate (MMA) and styrene (St) were studied. Phosphorus oxychloride (Cl₃P?O) and phenyl-phosphonic dichloride (C₆H₅Cl₂P?O) were used. Polymerization was carried out in benzene at 50°C by the standard solution method, α,α′-azobisisobutyronitrile (AIBN) being used as the initiator. In the polymerization of MMA, both phosphorus compounds increased the rate of polymerization. NMR spectral data suggested that this increasing effect was due to the complex formation between each phosphorus compound and MMA monomer. In the case of polymerization of St, NMR data also indicated the formation of a complex between the phosphorus compound and St monomer. Both phosphorus compounds showed an increasing effect for the rate of polymerization. Though these increasing effects could be explained by the complex formation, the polymerization of St in the presence of Cl₃P?O was especially found to be due to the cationic polymerization initiated simultaneously by Cl₃P?O in addition to the radical polymerization. These phosphorus compounds acted as chain-transfer agents in both polymerization systems. The parameters (Q_tr,_etr) which indicate the reactivity of a chain-transfer agent were calculated from the observed values of chain-transfer constant for both polymerization systems.     

Atom transfer radical polymerization of styrene initiated by triphenylmethyl chloride

Triphenylmethyl chloride (TPMCl) was employed for the first time as the initiator of atom transfer radical polymerization (ATRP) of styrene in the presence of CuCl/N,N,N′,N″,N″-pentamethyldiethylenetriamine (PMDETA) as catalyst and cyclohexanone as solvent. The kinetic plot was first-order with respect to monomer. A linear increase of number average molecular weight (M_n) vs. monomer conversion was observed, and the molecular weight distribution (MWD) was relatively narrow (M_w/M_n = 1.2-1.5). ¹H NMR spectra revealed the ω-Cl group at the chain end. Another two initiators, benzyl chloride (BzCl) and diphenylmethyl chloride (DPMCl), were also employed in contrast with triphenylmethyl chloride to investigate the influence of phenyl numbers on the polymerization.     

Cationic polymerization of 1,3-pentadiene in the presence of vanadium oxychloride

The cationic polymerization of 1,3-pentadiene in the presence of vanadium oxytrichloride is studied. 1,3-Pentadiene is shown to polymerize at a high rate to high monomer conversions in the absence of proton-donor compounds in the catalytic system. The initial rate of 1,3-pentadiene polymerization is proportional to the concentration of VOCl₃ in the system and demonstrates an extremal dependence on the initial concentration of 1,3-pentadiene. The polymerization process is distinguished by an induction period whose duration increases with a decrease in the reaction temperature. Regardless of polymerization conditions, with an increase in the monomer conversion, the molecular-mass distribution of the polymer widens owing to formation of a high-molecular-mass fraction, which, depending on reaction conditions, can be consumed in formation of the gel fraction. It is shown that the degree of unsaturation and the microstructure of poly(1,3-pentadiene) are almost independent of the polymerization conditions.     

A study of the polymerization of styrene initiated by K-THF-GIC system

In this paper, the polymerization of styrene initiated by potassium (K)-tetrahydrofuran (THF)-graphite intercalation compound (GIC) (K-THF-GIC) was studied. The mechanism of the polymerization was determined to be anionic polymerization according to its characteristics. The effect of the concentration of the initiator and monomer was studied. It was found that the polymerization mainly occurred on the surface and edge of the intercalated graphite. It was also shown that the polarity of solvent has little effect on the polymerization yield in this system.     

Cationic polymerization of p-methylstyrene initiated by acetyl perchlorate: An approach to living polymerization

The cationic polymerization of p-methylstyrene initiated by acetyl perchlorate at ?78°C led to long-lived (living-like) polymers with a narrow molecular weight distribution (M?_w/M?_n = 1.1–1.4) in methylene chloride containing a common ion salt (n-Bu₄NClO₄) or in a less polar solvent (CH₂Cl₂/toluene, 1/4v/v). Under these conditions, the number-average molecular weight (M?_n) of the polymers increased in proportion to monomer conversion and was regulated by the monomer-to-initiator ratio. When fresh feeds of the monomer were repeatedly added to a completely polymerized solution, the polymerization ensued at the same rate as before and the linear increase in M?_n with monomer conversion continued. The effects of solvent polarity and the common ion salt on the polymerization showed the suppression of the ionic dissociation of the propagating species, resulting in a “nondissociated species,” to be the key factor for the formation of the long-lived polymers.     

Cationic ring-opening isomerization polymerization of spiro orthocarbonates initiated by carbon black

The ring-opening isomerization polymerization of spiro orthocarbonates (SOC), such as 2,8-dimethyl-1,5,7,11-tetraoxaspiro[5.5]undecane ( I ), 8,10,19,20-tetraoxaspiro[5.2.2.5.2.2]-heneicosane-2,4-diene ( II ), and 8,10,19,20-tetraoxaspiro[5.2.2.5.2.2]heneicosane ( III ), initiated by carbon black was investigated. No polymerization of SOC was initiated in the absence of carbon black. But in the presence of channel black having a carboxyl group, the polymerization of SOCs was initiated at 90–150°C to give the corresponding polyether carbonates. The initiating ability of carbon black increased with an increase in its carboxyl group content. Furnace black having no carboxyl group failed to initiate the polymerization. Based on these results, it was concluded that the carboxyl group on carbon black is capable of initiating the polymerization of SOC. During the polymerization, a part of the polymers formed was grafted onto carbon black surface via the termination of growing polymer chains. The percentage of grafting increased with an increase in conversion and reached about 55%. Furthermore, polyether carbonate-grafted carbon black was found to produce a stable colloidal dispersion in chloroform. The mechanism of initiation and grafting were discussed.     

Cationic polymerization of vinyl monomers initiated by 10-methylphenothiazine cation radicals

A small quantity of 10-methylphenothiazine cation radical (MPT^.+), electrochemically prepared and stocked in acetonitrile solution, initiated cationic polymerizations of n-butyl, t-butyl, and 2-methoxyethyl vinyl ethers and p-methoxystyrene, while no initiation occurred for phenyl vinyl ether, styrene, methyl methacrylate, and phenyl glycidyl ether. ¹H-NMR studies of oligomers and low molecular weight compounds isolated from the reaction mixture for the polymerization of t-butyl vinyl ether in the presence of a small amount of D₂O indicated that electron transfer from the monomer to MPT^.+ was involved in the initiation step. ¹H- and ¹³C-NMR and MO calculation implied that monomers with higher electron densities on the vinyl groups and with lower ionization potentials were more susceptible to the initiation of MPT^.+. © 1994 John Wiley & Sons, Inc.     

2,3-二氰基-2,3-二苯基丁酸二乙酯引发苯乙烯的本体 聚合反应

在70～90℃对标题化合物外消旋异构体引发的苯乙烯本体聚合反应进行了研究,并与内消旋异构体、过氧化二苯甲酰和偶氮二异丁腈进行比较。结果表明,在本反应条件下,上述四种引发剂均能使聚合物分子量随反应时间的延续而增大,但C－C键引发剂对聚合物分子量及其链增长的影响远大于BPO和AIBN,这一现象应与α－氰基-α-乙氧甲酰基苄基自由基的结构特点有关。     

Cationic ring-opening transfer polymerization of spiro ortho esters initiated by carbon black

The ring-opening transfer polymerization of spiro ortho esters (SOE) initiated by carbon black was investigated. In the absence of carbon black, no polymerization occurred at all. In the presence of channel black containing carboxyl group, the ring-opening transfer polymerization of SOE was initiated at 50-70°C. to give polyether ester, namely alternating copolymer of epoxide and lactone. The rate of polymerization of 1,4,6-trioxaspiro[4.4]nonane and 1,4,6-trioxaspiro[4.5]decane was considerably small compared with that of 1,4,6-trioxaspiro[4.6]undecane. The activation energy of the polymerization of 2-chloromethyl-1,4,6-trioxaspiro[4.6]undecane was estimated to be 6.0 kcal/mol. The initiating activity of carbon black increased with an increase in carboxyl group content of carbon black. Furnace black that contained no carboxyl group was unable to initiate the polymerization. Furthermore, the carbon black lost the initiating ability of the polymerization upon the blocking of carboxyl group on the surface by the treatment with potassium hydroxide or diazomethane. Based on these results, it was concluded that carboxyl group on carbon black plays an important role in the initiation. During the polymerization, a part of the polymer formed was grafted onto carbon black: the grafting ratio was 10–30%. The mechanisms of initiation and grafting were discussed.     

Radical polymerization of styrene initiated by styrene–arsenic sulfide complex

Styrene forms a complex with arsenic sulfide which in DMF at 85°C initiates radical polymerization yielding high molecular weight polymer. The order of reaction, with respect to initiator and monomer, is 0.5 ± 0.02 and unity, respectively. The energy of activation for the system computed as 96 kJ mol^?1 and the polymerization is retarded by hydroquinone. A possible mechanism for reaction has also been proposed.     

Graft polymerization of styrene initiated by covalently bonded peroxide groups on silica

The graft polymerization of styrene initiated by immobilized peroxide groups was investigated. Three different types of modification reactions were used to introduce peroxide groups which are directly attached onto the surface of two different silica supports. Silanol groups were chlorinated using thionyl chloride or tetrachlorosilane. In another reaction pathway 1,3,5-benzenetricarbonyl chloride enabled the introduction of free acid chloride residues bonded onto the surface of silica. tert-Butyl hydroperoxide (TBHP) was used to transform the chlorosilyl and the acid chloride groups into peroxide residues. In a further reaction step the covalently bonded peroxides initiated the polymerization of styrene to form grafted polystyrene directly attached onto the silica support. Solid-state 13C CP/MAS NMR spectroscopy, and thermogravimetric and scanning electron microscope measurements enabled a clear structure and property elucidation of the different bonded phases. The highest amount of grafted polystyrene was achieved employing the acid chloride synthesis pathway with silica-gel, whereas modification of spherical silica only led to minor amounts of grafted polymer. The results contribute to the evolving need to understand particle surface modifications and may have positive impact on development of new HPLC stationary phases for improved elutant resolution.     

Cationic polymerization of styrene in a neutral ionic liquid

The cationic polymerization of styrene in a neutral ionic liquid, 1‐butyl‐3‐methylimidazolium hexafluorophosphate, with a 1‐phenetyl chloride/TiCl₄ initiating system is reported. The polymerization proceeds to a high conversion, but an analysis of the matrix‐assisted laser desorption/ionization time‐of‐flight spectra of the polymers indicates that chain transfer is significant, leading to a lack of control over the molecular weight and molecular weight distribution. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 3230–3235, 2004     

Cationic 1,2-vinyl addition polymerization of cyclic ketene acetals initiated by conventional acids

Pure 1,2-addition polymers, poly(2-methylene-1,3-dioxolane), 1b , poly(2-methylene-1,3-dioxane), 2b , and poly(2-methylene-5,5-dimethyl-1,3-dioxane), 3b , were prepared using the cationic initiators H₂SO₄, TiCl₄, BF₃, and also Ru(PPh₃)₃Cl₂. Small ester carbonyl bands in the IR spectra of 1b and 2b were observed when the polymerizations were performed at 80°C ( 1b ) and both 67 and 138°C ( 2b ) using Ru(PPh₃)₃Cl₂. The poly(cyclic ketene acetals) were stable if they were not exposed to acid and water. They were quite thermally stable and did not decompose until 290°C ( 1b ), 240°C ( 2b ), and 294°C ( 3b ). Different chemical shifts for axial and equatorial H and CH₃ on the ketal rings were found in the ¹H NMR spectrum of 3b at room temperature. High molecular weight 3b (M̄_n = 8.68 × 10⁴, M̄_w = 1.31 × 10⁵, M̄_z = 1.57 × 10⁵) was obtained upon cationic initiation by H₂SO₄. Poly(2-methylene-1,3-dioxane), 2b , underwent partial hydrolysis when Ru(PPh₃)₃Cl₂ and water were present in the polymer. The hydrolyzed products were 1,3-propanediol and a polymer containing both poly(2-methylene-1,3-dioxane) and polyketene units. The percentages of these two units in the hydrolyzed polymer were about 32% polyketene and 68% poly(2-methylene-1,3-dioxane). No crosslinked or aromatic structures were observed in the hydrolyzed products. The molecular weight of hydrolyzed polymer was M̄_n = 5740, M̄_w = 7260, and M̄_z = 9060. © 1997 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 35: 3707–3716, 1997     

Cationic polymerization of styrene on the surface of graphite expanded

Cationic polymerization of styrene initiated by the CO⁺ClO group on the surface of expanded graphite (EG) was carried out for modifying the surface properties of graphite. The initiating sites were achieved by the reaction of EG with SOCl₂ and followed by AgClO₄. Subsequently, the cationic polymerization of styrene was conducted to afford polystyrene brush on EG. The influence factors, such as polymerization time and temperature, on the polymerization including the grafting ratio and efficiency were investigated. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 2715–2721, 2003